The primary goal of this SCOR is to understand how human rheumatoid synovium is maintained in its chronic inflammatory state. This new information will help SCOR investigators propose and develop novel therapeutic interventions. To support these studies, a Research Resources Core will be created to help organize the collection of human clinical material as well as provide specialized support for the in vivo studies involving animal models of arthritis. The project requires human synovial tissue specimens, synovial mononuclear cells, or synovial fluid from patients with established and early rheumatoid arthritis (RA). One purpose of this core is to develop an implement an efficient, timely, and centralized mechanism for the acquisition and distribution of these research materials. Animal models of rheumatoid arthritis have also been used extensively to study the pathogenesis of chronic inflammatory arthritis. Proper conduct and evaluation of these animal models requires specialized expertise to ensure reliable and interpretable results. Therefore, the Core will help coordinate and centralize the efforts of the investigators and provide ready access to experienced investigators in animal models of arthritis.